The present invention relates, in general, to electrical connectors, and, more specifically, to radially resilient electrical sockets, also referred to as barrel terminals, in which a cylindrical electrical prong or pin is axially inserted into a socket whose interior surface is defined by a plurality of contact strips or wires mounted within a cylindrical sleeve and inclined between opposed ends.
Radially resilient electrical sockets or barrel terminals are a well known type of electrical connector as shown in U.S. Pat. Nos. 4,657,335 and 4,734,063, both assigned to the assignee of the present invention.
In such electrical sockets or barrel terminals, a generally rectangular stamping or sheet is formed with two transversely extending webs spaced inwardly from and parallel to opposite end edges of the sheet. Between the inward side edges of the transverse webs, a plurality of uniformly spaced, parallel slots are formed to define a plurality of uniformly spaced, parallel, longitudinally extending strips which are joined at opposite ends to the inward side edges of both transverse webs. Other longitudinally extending slots are coaxially formed in the sheet and extend inwardly from the end edges of the blank to the outer side edges of the transverse webs to form a plurality of uniformly spaced, longitudinally extending tabs projecting outwardly from each transverse web.
The blank or sheet is then formed into a cylinder with the longitudinal strips extending parallel to the axis of the now cylindrical sheet. A closely fitting cylindrical sleeve is slipped coaxially around the outer periphery of the cylindrical blank, and extends axially substantially between the outer side edges of the transverse webs. The tabs at each end of the blank are then bent outwardly across end edges of the sleeve into radially extending relationship to the sleeve.
A relatively tight-fitting annular collar or outer barrel is then axially advanced against the radially projecting tabs at one end of the sleeve and slipped over the one end of the sleeve driving the tabs at that end of the sleeve downwardly into face-to-face engagement with the outer surface of the one end of the sleeve. The fit of the annular collar to the sleeve is chosen so that the end of the cylindrical blank at which the collar is located is fixedly clamped to the sleeve against both axial or rotary movement relative to the sleeve.
A tool typically having an annular array of uniformly spaced, axially projecting teeth is then engaged with the radially projecting tabs at the opposite end of the sleeve. The teeth on the tool are located to project axially between the radially projecting tabs closely adjacent to the outer surface of the cylindrical sleeve. The tool is then rotated about the longitudinal axis of the cylindrical sleeve while the sleeve is held stationary to rotatably displace the engaged tabs approximately 15° to 45° from their original rotative orientation relative to the sleeve and the bent over tabs at the opposite end of the sleeve. The tool is then withdrawn and a second annular collar or outer barrel is force fitted over the tabs and the sleeve to fixedly locate the opposite end of the blank in a rotatably offset position established by the tool.
When completed, such an electrical socket has longitudinal strips extending generally along a straight line between the angularly offset locations adjacent the opposite ends of the cylindrical sleeve. The internal envelope cooperatively defined by the longitudinal strips is a surface of revolution coaxial to the axis of the cylindrical sleeve having equal maximum radii at the points where the strips are joined to the respective webs and a somewhat smaller radius midway of the length of the strips. The minimum radius, midway between the opposite ends of the strips, is selected to be slightly less than the radius of a cylindrical connector pin which is to be inserted into the barrel socket so that the insertion of the pin requires the individual longitudinal strips to stretch slightly longitudinally to firmly frictionally grip the pin when it is seated within the barrel socket.
To put it another way, because of the angular offset orientation of the opposed ends of each of the strips, each strip is spaced from the inner wall of the sleeve in a radial direction progressively reaching a maximum radial spacing with respect to the outer sleeve midway between the ends of the sleeve.
Such a radially resilient electrical barrel socket provides an effective electrical connector which provides secure engagement with an insertable pin; while still enabling easy manual withdrawal and insertion of the pin relative to the socket.
Other approaches to simplify the locking of the ends of the contact strips in the angularly offset position relative to the sleeve have also been devised. One such approach is the formation of axially extending grooves or splines in the interior of the sleeve. The grooves receive the ends of the contact strips of the contact member after one of the ends has been angularly offset relative to the other end to fixedly secure the ends of the contact strip in the desired angularly offset position without the need for outer mounting sleeves.
While the grooves or splines eliminate the need for outer sleeves to retain the ends of the contact strips in the angularly offset position relative to each other and to the sleeve, it is believed that further improvements could be made to a radially resilient electrical barrel socket to afford a simplified construction, and manufacturing sequence while still retaining the features of securely holding the ends of the contact strip in the angularly offset position without the need for outer end sleeves.